Can men and women be 'just friends'?

Just friends? – Friends Timothy Goodman, 32, and Jessica Walsh, 26, dated for 40 days as an experiment. Their blog, 40 Days of Dating, has gone viral.

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Just friends? – Nora Ephron's 1989 romantic comedy, "When Harry Met Sally," famously explored the trope of male-female friendships. "What I'm saying is -- and this is not a come-on in any way, shape or form -- is that men and women can't be friends because the sex part always gets in the way," said Harry Burns, played by Billy Crystal.

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Just friends? – Ron Weasley and Hermione Granger of the Harry Potter series -- played by Rupert Grint and Emma Watson in the films based on the books -- couldn't resist each other's charms, and the two eventually marry.

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Just friends? – Rachel Green, played by Jennifer Aniston, and Ross Geller, played by David Schwimmer, made the ultimate will they-won't they relationship for viewers. In 10 seasons of "Friends," fans saw the couple get together and break up multiple times; they ultimately end up together.

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Just friends? – Julia Roberts realizes she has feelings for her best friend, played by Dermot Mulroney, in the 1997 film, "My Best Friend's Wedding."

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Just friends? – Friends Dylan and Jamie, played by Justin Timberlake and Mila Kunis, decide to have a physical relationship in the 2011 film, "Friends with Benefits."

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Just friends? – Niles Crane, played by David Hyde Pierce, was infatuated with Daphne Moon, played by Jane Leeves, from the first of 11 seasons of "Frasier." Moon and Crane finally married in the first episode of the 10th season.

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Story highlights

Two friends from New York City decided to try dating -- and blog about it

The blog, 40 Days of Dating, details their relationship, which began in March

Blogger: "We used it as a catalyst to work on our issues together"

Truly platonic opposite-sex friendships are the chupacabra of the pop culture narrative. From "When Harry Met Sally" to Ross and Rachel, first comes friendship, then comes relationship.

Longtime friends Timothy Goodman, 32, and Jessica Walsh, 26, have taken to exploring the leitmotif once more -- and in a 21st century twist, decided to share it with the world via their blog, 40 Days of Dating.

The two friends met more than four years ago through New York City's graphic design community. When they both found themselves single at the same time, they decided to embark on the social-turned-design experiment.

"Tim is afraid of commitment, often dating many girls at once, and he's losing sight of what a healthy relationship means," the couple explains on the blog. "Jessica is a hopeless romantic, jumping into relationships too quickly, always looking to find 'the one.' "

First, they set the ground rules for the experiment, which started in mid-March:

1. They would see each other every day for 40 days.

2. They would go on at least three dates a week.

3. They would see a couples therapist once a week.

4. They would go on one weekend trip together.

5. They would fill out a daily questionnaire and document everything.

6. They would not see, date, hook up or have sex with anyone else.

They began adding new posts about the relationship only after the 40 days were up. They've been posting entries Monday through Friday since July 10, and they'll continue until August 22, when readers will learn how their experiment ended.

"We didn't want to do this live because if we read each other's questions, we'd be influenced by each other and by the public's perception of it," Goodman said.

Their readership has grown so much that both Walsh and Goodman have had to retroactively monitor their social media accounts to prevent spoilers. The couple wouldn't offer any hints about the outcome -- they suggest people stay up-to-date with their romantic escapades via the website.

Goodman and Walsh spoke to CNN separately about the online dating project and the age-old question, can men and women really just be friends? The interview has been edited for clarity and brevity.

CNN: Why'd you choose to do the project with each other?

Goodman: We always were kind of dumbfounded with each other's relationship issues and would make fun of each other's relationship issues all the time.

Walsh: I had basically, since the time I was 16, jumped from relationship to relationship up until a year and half ago when I ended a relationship with a guy I had lived with. Since then, I had been looking -- and New York City is such a tough place to find a guy. It was just a terrible year of dating. It was just the right time when we started talking about it.

CNN: You've been friends for more than four years. Was there always an attraction?

Goodman: It's always been platonic, but we wouldn't have been able to do this project if there hadn't been some curiosity. I've always been attracted to Jessie; I know she's beautiful. We're very different though; I'm more outgoing, she's more reserved.

Walsh: He's not my usual type, I always thought he was a very attractive guy. I have a lot of respect for the work that he does -- I can't deny that there.

CNN: Were you ever worried that the experiment would ruin the friendship?

Walsh: I was pretty excited about it at first, then after we told our friends, I did start to get scared that this could totally destroy a great friendship. We didn't want to compromise, so it was a few months after we had the initial idea before we actually started because we kept going back and forth.

CNN: You're obviously both creative people, and the site itself is very artistically driven. How did you separate the creative showmanship with the relationship?

Goodman: What's important is that it's an experiment. For it to be a success, it doesn't mean that Jessie and I worked out together. We used it as a catalyst to work on our issues together; a safe space to work on our issues and also to help each other. Sure, there were other things going on and there had always been a curiosity about it. This isn't just about dating, that's not the point -- it's taking two mice with two different problems and seeing what happens.

Walsh: We tried to keep them very different. We did the experiment first because we did want the experiment to be as true as possible, and not have the creative side get in the way of it. This is the best way we knew how. Each time we read each other's, we're reliving the day in a way. In some of the more emotional days, it brings back everything. It hasn't been easy.

CNN: The rules are quite fastidious for something so unpredictable as a relationship.

Goodman: We knew that if we didn't have rules in place, it would be very easy for us to skip by. The rules held us accountable.

Walsh: It's kind of a theme in the work that I do, I always set constraints. The best outcomes come from restraints. Forty days is also the amount of time in several religions that it takes to break a bad habit. The couples therapy was one stipulation that I really wanted. It was amazing week to week to have that hour to sit down and really be able to reflect and have a third party to help you organize and sort through what happened and give you that objective advice. I honestly don't think we would've made it through the 40 days without it.

CNN: In the early days of the blog, your friends criticized you both for not being physical. You left those constraints pretty ambiguous. On day 25, readers learned, that changed.

Goodman: We had left that open. It was bit of an issue right in the beginning because her friend was giving her (a hard time) about it. She got weird about it. We can't just click our fingers and be in a relationship. There was a lot of push and pull because of it. I didn't know what my intentions were.

Walsh: I had wanted it for a while. I was just like, "Let's try this." We both admitted on day two of the therapy that there was attraction, there was some interest. Tim was the one that was super scared because his issues are quite real. We had a great friendship, so he was very, very hesitant -- but it was confusing for me because he would be flirtatious.

CNN: So, do you think men and women can ever be just friends?

Goodman: I have girlfriends that I consider just girls who are friends now, but it's only because I've been with them before or they're in a relationship so you don't have to even think about it. If you asked me a couple of months ago, I would've said yes. In one of his stand-ups, Chris Rock said every platonic friend that he had was someone he was trying to sleep with, made a wrong turn somewhere and ended up in the "friend zone." I think there's truth in that. A man always has a motive.

Walsh: I do.

CNN: Well, what happened?

Goodman: I will say that I feel forever linked to her. I have this kinship with her because of it, regardless of what happened or if we're together or we're not.